United States Olympic boxer Claressa Shields took another step closer Monday to fulfilling her dream of coming home to Flint, Mich., with an Olympic gold medal from London, winning her first bout of the games to advance to the semifinals of the women's middleweight division.

"I didn't run around the ring after I won like a maniac because my work's not done yet," said Shields, 17, according to NBC. "But I'm thankful to God, thankful to everyone at home going crazy supporting me in Flint, thankful for my coach Jason Critchfield, and my team who I train with. I'm not done yet until I get that gold."

Shields defeated Sweden's twice-former world champion Anna Laurell after trailing in the first round and heading into the final fourth round tied. She ended with "a ferocious fourth round flurry," as The Associated Press reported, to win on points 18-14. Shields caught Laurell with a hard left in the fourth round, causing a standing eight-count for the Swede.

It is the first time in Olympics history that women's boxing will be a medal sport and Shields is the youngest U.S. boxer in 40 years. The high school junior's quest for Olympic gold and a successful boxing career is being documented for the movie about her life titled, "T-Rex" (her boxing nickname).

Shields' story is coming into more clarity and detail with each glowing account of her boxing matches. It's one that includes being sexually abused as a young girl, a troubled family life, and growing up in an area with a high rate of violent crimes.

"I box for a lot of reasons," said Shields during a London Olympics press conference. "To show you can come from a real small city where you're not really acknowledged and you can become something.

"I fight because I feel it is the best thing I am good at winning at. I want to win. I want to be successful," she continued.

"I've lost so many of my friends ... the last two summers, I had a total of four friends (killed) I was never able to go to their funerals. Gun violence," she said.

She mentioned the name of a friend that was killed in seven days of violence that included seven deaths.

"There's nothing I can do about it. I just pray to God to protect my family to protect my friends and I pray for Flint especially," she said.

NBC Olympic boxing producer Ryan Maquiñana ‏tweeted after Shields' victory on Monday: "Talking 2 @ClaressaShields you'd think a 10yr pro vet [was] on the line as composed w the media as she was today in her W."

"She has the most incredible coping skills of anyone – of any age – that I have met," Johnson said. "She channels all of her anger, all of the disappointment around her into strength, and I don't just mean her razor sharp jab. She is singularly focused. She works out her emotions in her journal constantly.

"She's redefining what it means to be a survivor. And she's redefining what it means to be a girl. I want every young woman in America to see her story. She has a lot to share with all of us," Johnson added.

About 70 people, including members of her family, gathered at a local restaurant in Flint to watch Shields' match on TV on Monday.

Claressa's father Clarence Shields "shed tears of joy after the match," according to The Flint Journal.

"I always cry every time she fights," said Clarence Shields, while wiping his eyes. "I feel good. Honestly, I expect her to win and I don't expect less because that's what she said she was going to do.

"I think she was a little slower than she normally is but all of her opponents are runners and they ought to be on the track and field team instead of the boxing team," he said. "But now everybody in the world knows that Claressa's the best fighter in the world at 165 pounds. I believe my baby is the baddest 165 pound fighter in the world."

Shields will fight Marina Volnova of Kazakhstan in the semifinals on Wednesday. Volonova upset top-seeded Savannah Marshall of Great Britain.